Mechanical pencil



July 1, 1930. c. R. KEERAN MECHANICAL PENCIL Filed Dec. lO, 1928 efdzz,

Patented `Fully l, 1930 PATENT OFFICE CHARLES R. KEEBAN, OF EVANSTON,ILLINOIS MECHANICAL PENCIL Application filed December 10, 1928. SerialNo. 324,854.

The invention relates to mechanical pencils, and its purpose is toprovide an improved pencil construction of relatively few parts ofsimpliied and durable design which facilitate the assembly operation andwhich, as a whole, may be manufactured economically.

It consists in certain features and elements of construction incombination, as herein shown and described, and as indicated by the 1nclaims.

In the drawings Figure l is an enlarged axial section of a mechanicalpencil constructed in accordance with the present invention.

Figure 2 is a side view of the guide tube of the barrel, with the erasersocket structure secured to its upper end, shown in section.

Figure 3 is a trans-axial section taken substantlally as indicated atline 3-3 on Figure 1.

Figure 4 is an enlarged fragmentary axial section of certain parts oflead-propelling mechanism.

Figure 5 is a side elevation of the pencil shown provided withgraduations as a scale for linear measurement.

Figure 6 is a fragmentary view of the upper end of the pencil, showingthe cap in exao tended position for increasing the length of the scaleto an exact number of units of measurement.

As illustrated in the drawings, the pencil includes a tubular body orbarrel, 10, formed of any suitable material, such as wood, bakelite,various molded compositions, or metal, having one end provided with areduced tapered portion, 11, on which is removably mounted a rotatabletapered tip, 12. rlhe barrel is formed with a straight bore, 13,preferably annular, extending froml end to end, and securely mounted inthe upperend of the bore is a bushing, 14, extending a substantiallength of the bore'. Firmly mounted (as by drive or force fit) in thebushing is the upper end of a guide tube, 15, which is disposedconcentrically in the bore, and is substantially co-extensive with thebarrel.

The upper end of the bushing is counterbored for the shank, 16, of thehead sleeve,

17, which is preferably rigidly secured to the upper end of the guidetube, 15. The shank, 16, being inwardly offset from the sleeve proper,forms an annular shoulder,18, adapted to be seated against the upper endof the barrel, as shown in Figure 1, for insuring proper positioning ofthe guide tube. To facilitate the assembly operation in general, it maybe desirable to first assemble as a unit A the guide tube, head sleeveand the bushing,

and insert in position in the barrel. The bushing is provided with a.longitudinal way, 19, in its outer periphery for engaging the tang, 20,of the clip, 21, 'for firmly securing the same. in position.

The lower end of the guide tube being unsupported and in spaced relationto the wall of the bore, 13, forms an annular spare-lead chamber ormagazine, 23, for leads, 24, the chamber opening at the end adjacent thetip;

the inner end of the bushing serving to define the bottom of thechamber. This arrange-V ment is` particularly advantageous in that itaffords access to the spare lead chamber simultaneously upon the removalof the tip from the barrel. Although the upper end of the guide tube,15, is firmly supported in the bushing, the lower. end beingunsupported, and in a sense floating, is free to be flexed slightly outof its normal axial plane for a purpose hereinafter described. The innerend of the bushing preferably terminates at such a point that the sparelead chamber, 23, will have considerable depth for receiving relativelylong leads of, say, two-inch lengtlr or greater, as compared to theusual inch and a half length leads provided for most pencils of thischaracter.

The tapered tip, 12, is in the nature of a hollow shell of substantiallyconical formation, made of thin sheet metal. In forming the tip, theportion. adjacent the apex is swaged in a manner to cause the metal toflow inwardly forming a terminal, 26, integral with the walls of thetip, and of a. length several times the thickness of the wall, thusinsurino' proper support and guidance for the lead, 24a, as it is fedtherethrough. The terminal may be slitted to provide a yieldingfrictional grip on the lead as it is fed therethrough. Firmly securedconcentrically in vthe tip is a lead tube, 27, of relatively thick 30,internally threaded for engagement with the threaded portion, 31, of aplun er, 32, which is longitudinally movable in t e lead tube and alsoin the guide tube when tele. scoped therein, as shown, in Fi re 1. Theplunger which normally vis yie dingly held against rotation is providedwith the same safety feature disclosed in my co ending application,Serial No. 303,647, file September 4, 1928, to prevent injury orbreakage of parts due to jamming of the lead, or when the plunger hasreached the limit of its longitudinal movement. As shown in the drawingsthis feature consists of a hollow resilient head, 34, of substantiallytubular shape, rigidly fastened to the upper end of the plunger, 32,which co-operates with the inner surface of the guide tube, 15; thispart of the tube being polygonal in cross-section,-v

herein shown as hexagonal. The polygonal formation of the guide tubeextends through that portion of the length thereof which corresponds tothe lead-feeding range of the plunger, 32, but the extreme lower end ofthe tube may be cylindrical to serve as a bearing for the lead tube, 27.The hollow head, 34, is longitudinally slitted to make it resilient, andthe portions between the slits are provided with outwardly projectingnodes, 35, which are adapted to be positioned in V- grooves formed bythe abutting walls of the guide tube, and thus provide proper guidancefor the plunger as it is propelled longitudinally. The nodes yield topermit rotation of the plunger only when there is an' obstruction to thelongitudinal movement of the lunger, such as mentioned above.

T e portion of the lead tube telescoged into the guide tube being ofconsidera le length, affords la substantial bearing, and also providesample friction to maintain adjustment. Due to the fiexibility of theunsupported lower end of the guide tube, proper alignment of the arts inco-operative relation wit-hout un ue binding when the tip is mounted onthe barrel is assured even if the lead tube is slightly off center.Notwithstanding this flexibility, the tip is fitted firmly on the barreland permits smooth and easy movement of the parts. It is apparent thatif the lower end of the guide j Atube were rigidly supported it would beimpossible to secure this accommodation of the guide tube to the leadtube. As will now be apparent the lead propeller mechanism operates in ausual manner by the relative rotation of the tip and barrel, moving theplunger longitudinally for forcing the lead through the tip. To insert anew lead in the lead tube, .the tip and barrel are first separated, butpreferably before actual separation the point may be tilted downwardly,causing the spare lead in the magazine to strike the washer, 28, so thatwhen the tip and barrel are separated in horizontal position, the endsof the leads in the magazine will extend a short distance beyond the endof the barrel so as to facilitate the selection of a new lead.

The portion of the tip adjacent the base of the cone is concavely curvedas indicated at 38, to provide a convenient finger engaging portion,thus tending to prevent slippage of the finger on the tip. The apex ofthe terminal, 26, is drawn straight for a short distance, and thisformation taken with the concave portion, 38, in general causes theentire wall of the tip to appear concavely curved.

The basel portion of the tip is shaped to snugly fit the taperedportion, 11, of the barrel in a wedging manner to provide sufiicientfriction against relative rotation of the tip and barrel. As the taperedportion, 11, wears down, the edge of the tip cuts into the shoulder, 11,to take up the wear and thus insures proper fit of these co-operatingparts.

Seated in the fixed head sleeve, 17, is an annular eraser sleeve, 41,encompassing a plurality of yieldable eraser gripping prongs, 42, of asocket, 43, in which is firmly held an eraser, 44. The prongs, whichnormally tend to separate at their free end, are formed with inwardlyprojecting jaws, 45, for gripping into the eraser. By such anarrangement a long eraser may be used, and the eraser may be adjusted,from time to time in the jaws, as it is worn down, so that practicallythe entire eraser may be utilized. It will be understood that the prongswhen free, are out of contact with the eraser, but upon sliding thesleeve over the prongs toward their free end, their jaws are forciblyprojected into the eraser. The outer end of the sleeve, 41, is formedwith an annular enlargement, 46, adapted to abut against the upper edgeofthe head sleeve, 17, preventing it from being moved totally within thehead sleeve. The enlargement abutting the edge of the head sleeve, 17,insures that the sleeve, 41has roperly constricted the prongs topositivey hold the eraser. The enlargement also serves as a convenientgrip for removing it and the eraser socket from the head sleeve. It willbe noted that the eraser sleeve, is of less length than the erasersocket, so that upon removal of both as a unit, the eraser socket may beeasily ejected from the eraser sleeve to permit adjustment of the eraserin the jaws of the prongs. Snugly telescoped on the head sleeve,enclosing the eraser, is a usual head or lcap, 47, of suitableornamental design.

As illustrated in Figure the tip, barrel and head of the pencil areprovided with two series of graduations forming continuons scales forlinear measurement in both Engif lish and metric systems. rlhe Englishscale starts at the end of the tip and the graduations are indicated ininch units on the tip, barrel and head;A the graduation at the end ofthe first unit of measurement being` adjacent the point at which thecurved portion, 38, commences from the straight taper of the tip. Forconvenience the first unit is graduated in fractional inch units. Asdesigned, the pencil is less than an exact number of units in length andinasmuch as the overall length of a pencil could be advantageouslyutilized as a unitmeasuring stick, I have provided the head sleeve withgraduations corresponding to the graduations of the head when inposition. By this arrangement the head may be extended outwardly on thesleeve to a predetermined position, as by aligning the inner edge of thehead with a mark on the head sleeve (indicated at a,) so that the lengthfrom the end of the tip to the outer end of the head is an exact numberof units, herein representing six inches. This feature has the advantageof being capable of application to the conventional pencil, withoutimposing any restrictions as to length.

The graduation for the metric system commences at the beginning of theconcavely curved portion, 38, and at the end of the first inch unit ofthe English system, and extends to the outer end of the barrel. The tipis designed so that the distance from the begin ning of the concavelycurved ppr'tion to the edge of the tip is one centimeter, which isdivided into millimeter graduations for convenience of measurement. Themillimeter graduations of the first centimeter, which occupies the baseor curved portion of the tip, are formed as circumferential scoremarkings or grooves, as shown in the drawing.'

Making the graduations at this curved p0rtion circumferential, breaks upthe smooth surface which tends to further prevent slipping cfg/thefinger along the tip of the pencil.

By virtue of the floating or iexible mounting of the tube, 15, and alsothe free projection of the tube, 27, from its securement in the tip, Ican obtain additional friction between these tubes when they aretelescoped together by employing a slight' initial deformation or bendin,of the tube, 27, as more fully disclosed an explained in my pendingapplication Serial No. 197,7 93, filed June 10, 1927. Such curvature ofthe tube, 27, will merely exert a stress against the tube, 15, tomaintain any position of` adjustment of the tip and the lead therein.

sinsure a relatively snug lit of the tip on the barrel, and adapted totake up the wear of the reduced end of the barrel, the `edge of the tipserving to cut back the shoulder of the barrel as the reduced portionwears down.

2. A mechanical pencil comprisinga barrel and a removable tip at oneend, said tip being of substantially conical formation, the portion ofthe tip adjacent the base of the cone being provided with a plurality ofcircumferential corrugations, providing a con-y venient linger grip,said corrugations beingl axially spaced so as to serve as graduations 0fa scale for linear measurement. Y

3. A mechanical pencil comprising a barrel, a removable tiptelescopically associated therewith at one end, said barrel having alongitudinal bore, 'a guide tube concentrically disposed in the bore andfirmly secured at its upper end in the .bore of the barrel, the oppositeend of the tube adjacent the tip being unsupported and adapted toper'mit slight flexing thereof out of axial alignment, and a plungeroperatively associated with the tube and tip for feeding a leadtherethrough.

4. A mechanical pencil comprising a barrel provided with a longitudinalbore, a removable tip rotatably engaged with one end of the barrel, aguide tube disposed concentrically in said bore and firmly securedtherein at its upper end, the lower end of said tube being in spacedrelation in the bore to form an annular spare-lead magazlne opening atthe end adjacent the tip, and a plunger operatively associated with theguide tube and the tip for propelling a lead therethrough.

5. A mechanical pencil comprising a barrel having a longitudinal bore, aremovable tip engaged with one end of the barrel, a guide tube disposedcentrally in the bore and firmly secured therein at the upper end, the

-lower end of the tube being'unsupported in the bore and adapted to beyieldingly flexed out of axial alignment,'a lead tube secured to the tipand adapted to be telescoped into the lower end of said guide tube, anda plunger having threaded engagement with the lead tube andlongitudinally movable but, held against rotation in said guide tube forfeeding a lead through the tip.

6. A mechanical pencil comprising a barrel provided with a boreextending longitudinally from end to end, a removable tip telescoped onthe lower end of the barrel, a bushing secured in the upper end of thebore, a guide tube of substantially the same length as the barrel andfirmly secured at its upper end in said bushing, the lower end being inspaced relation in the bore forming an annular spare-lead chamber, theinner end of the bushing serving as the bottom of the chamber, :L leadtube secured to said tip, having an extended portion adapted to betelesooped into the lower end of the guide tube, and a plunger havingthreaded engagement with the lead tube and being longitudinally movablein the guide tube for feeding a lead through the tip.

CHARLES R. KEERAN.

